Diagnosis and
biological behavior of breast cancer of female dog represent one of the biggest
challenges facing the Veterinarian in recent years. Due to its exponential
growth and the degree of aggressiveness, the exact cause of this tumor is
probably multifactorial and it is believed that may suffer influence from
environmental factors. Among the suspected environmental contaminants are the
pyrethroids. Aiming to investigate the participation of pyrethroids in tumorigenesis
in female dogs, a study was conducted using 50 female dogs, 22 were positive
for simple breast carcinoma (Group I), 18 with a diagnosis of complex breast
carcinoma (Group II) and 10 negative (Group III) for breast cancer.In order to detect DNA damage, the
Comet assay was performed on mammary samples of these animals, which also had
samples submitted to the technique of High Performance Liquid Chromatography (HPLC), which aimed to quantify the
concentration of pyrethroids. The results of HPLC of each animal were compared
with those obtained by the Comet assay analysis of variance and the means were
compared by the test groups “Student T” at the significance level of p￡0.05. Despite presenting correlation
between the amount of DNA damage and tumor aggressiveness, no statistical differences
were found in the DNA damage of different histologic types of breast carcinoma.
As for pyrethroids, even these were detected in 22% of tumor tissues and
peritumoral fat, there was no difference in DNA damage between cells exposed
and not exposed to environmental contaminant.

International Agency for Research Cancer, “IARC: Overall Evaluations of Carcinogenicity to Humans,” International Agency for Research Cancer, Lyon, 1987.
http://monographs.iarc.fr/ENG/Monographs/vol53/mono53-10.pdf